This invention relates to a control unit for an electro-hydraulic roof support control arrangement, and to a control unit/hydraulic control mechanism for such a control arrangement.
A known type of control unit/hydraulic control mechanism of this type has a plurality of hydraulic control valves mounted on a distributor plate, the control valves and the distributor plate constituting the hydraulic control mechanism. The control unit contains electromagnetic valves which are used to actuate the control valves, which in turn control the operations of the various hydraulic working appliances of, for example, a mine roof support unit. Known hydraulic and electro-hydraulic roof support control arrangements can be controlled, via electric cables, from a central control stand disposed in the gallery or at the end of the face. Each roof support unit is provided with a control unit/hydraulic control mechanism which enables the hydraulic working appliances of that roof support unit to be controlled in various ways. For example, the hydraulic working appliances can be controlled automatically and sequentially from the central control stand, optionally from either the right-hand or left-hand adjacent roof support unit, or individually by manual or automatic control.
By providing each of the control units with a programmable electric control box, it is possible to effect continuous monitoring of the equipment at the face from the central control stand. In other words, all the roof support units at the face can be supervised from the central control stand, and all the control units can be electrically actuated so that the associated hydraulic control valves carry out a predetermined programme. In this system, the control units can be such that the required work operations, that is to say the programmes stored in the electronic control boxes, can be initiated not only from the central control stand, but also at the individual control units. Usually, this is achieved by manual operation of the individual control units, but this is only possible provided a "release signal" has previously been sent from the central control stand. In such a system, each of the electronic control boxes may also include a selector switch for designating the desired form of control, for example, automatic sequential control, control from the left or the right, individual manual control, or individual automatic control.
The aim of the invention is to provide a control unit and a control unit/hydraulic control mechanism, which can be made from a plurality of individual sub-units, which is compact, easy to assemble, and readily adaptable to suit different control functions.